
MKVToolNix GUI (multiplexer): when trying to add thumbnails for a Blu-ray the GUI will determine the thumbnail’s pixel size from the thumbnail files if the XML file doesn’t contain that information.mkvmerge (WAV reader): added support for reading RF64 files.Also, line edits and combo boxes will now have a "clear text" button appear whenever they are not empty. The list of predefined track names is now split into 3 lists, one for each track type (audio, video and subtitles). The new 41.0.0 version also adds improvements for predefined track names to the MKVToolNix GUI.

Previously when importing VP9 or Opus from MP4, the audio wasn't playable and extraction wasn't possible (the codecs were shown as QuickTime and the extraction of such files is not supported).
MKVTOOLNIX MKV MP4
The latest release also adds support for reading Opus audio and VP9 video from MP4 files. This has been implemented for both the Matroska and Ogg readers.

With the latest MKVToolNix 41.0.0, Vorbis, Opus and VP8 stream comments (Vorbis comments) are converted to Matroska attachments for cover art, and Matroska track tags for other comments. The tools are available on Linux, *BSD, Windows and macOS. MKVToolNix is made of 4 command line tools: mkvmerge (create Matroska files from other media files), mkvinfo (show Matroska file information), mkvextract (extracts tracks / data from Matroska files), and mkvpropedit (change the properties of existing Matroska files without a complete remux), as well as MKVToolNix GUI (a Qt GUI for mkvmerge, mkvinfo and mkvpropedit). MKVToolNix, a free and open source set of tools for creating, editing and inspecting Matroska (MKV, MK3D, MKA, and MKS) files, has seen a new release which brings support for reading Opus audio and VP9 video from MP4 files for mkvmerge, improvements for predefined track names, and more.
